Process of making relief-plates



(No Model.)

J. F. BARHAR'T; PROCESS OF MAKING RELIEF PLATES.

Patented Nov. 21, 1893.

FIG-.1.

FIG-.3

m5 NATIONAL umosanmms COMPANY.

wAsmmataN. 04 c.

UNITED STATES PATENT OFFICE.

JOHN F. EARHAR'I, OF CINCINNATI, OHIO.

PROCESS OF MAKING RELIEF-PLATES.

SPECIFICATION forming part of Letters Patent N 0. 509,120, dated November 21, 1893.

Application filed March 6. 1893. Serial No. 464,639. (No specimens-l To all whom it may concern:

Be it known that I, J oHN' F. EARHART, a citizen of the United States, residing at Oincinnati, in the county of Hamilton and State of Ohio, have invented a certain new and useful Method of Making Relief-Plates; and I do hereby declare the following to be a full, clear, and exact description of the invention, reference being had to the annexed drawings, which form part of this specification.

My invention comprises a novel process for the expeditious production of relief plates to be usedin printing those' peculiar illustrations commonly known as half-tone engravings or process pictures, the object of the improvement being to render such prints as soft and delicate as an original photograph,

or photogravure, and consequently, much superior to the ordinary process pictures, halftone engravings, lithographs, &c. To accomplish this result, I employ two or more relief plates for producinga single picture, and the first one so used will hereinafter be referred to as the original or complete-plate,while the others will be designated as shadowplates. This original plate, together with the required number of shadow-plates are, in their first stages, prepared in the same manner as those used for printing ordinary half-tone engravings, all of said plates being produced from a single photographic positive or negative. But the shadow-plates are subsequently treated to a special operation,which constitutes the essential feature of my invention. This special preparation of the shadow plates will hereinafter be alluded to as over etching, and the method of carrying out said operation, together with the combined effect said plates have in producing a finished print, will be readily understood by referring to the annexed drawings, in which Figure 1 represents an original or complete plate to be used in printing a landscape illustration. Figs. 2 and 3 represent a pair of shadow plates, of successively diminishing surfaces, to be used in connection with said complete-plate. Fig. 4 shows a finished print produced by these three plates.

Referring to Fig. 1. A represents an original or complete relief-plate composed of any metal or composition of metals, or other material capable of being etched by an acid or other corroding agent or agents. This reliefplate has a picture photographed on it, either from a negative or positive that has been prepared in the same manner as those used for producing half-tone engravings or process pictures, and said plate is then eaten away like the plates used in printing such illustrations, the result being an exact copy of the original photograph. Evidently, this photograph can be taken from any object it is desired to illustrate, but in the present case a landscape is represented, including a reservoir of Water, a pumping station adjacent thereto, a river, distant hills and sky, and it is supposed three relief-plates will be necessary to produce a good effect with such a comprehensive subject. Therefore, when this original plate A is prepared, two more precisely-similar plates B, C, are made from the same photographic positive or negative, in order that these three plates A, B, 0, may be, in the beginning, exact fac-similes, of each other. But when the plate B is'etched, the acid, or other corroding agent, is allowed to act for a sufficient length of time to eat away all the fine and delicate parts of said plate, as seen in Fig. 2. Reference to this illustration shows that the sky, distant hills, and reflections in the water have disappeared, and that the dark tones and extreme edges of all masses in the middle distance have been materially softened by the action of the corroding agent, the result being the production of the first shadow-plate.

The second shadow-plate 0, represented in Fig. 3, is produced by allowing the acid. to act for a still longer'period, or in other words, until the entire middle distance is eaten away and nothing is left of the picture except the deep shadows and dark objects in the immediate foreground, such as the trees at the sides of the picture and the near shrubbery,the extreme edges of these remaining objects being also softened or toned down by the corroding agent. These two shadow-plates, B,

0, show very clearly the result of over etching them, or in other words, they show that, although the acid has attacked all lines alike, yet. it has destroyed those lines only which are relatively fine or narrow, and consequently, have a large side surface in proportion to their upper surface. In this respect,

the acid acts as a tool that automatically and unerringly removes the very parts not needed,

and thus takes the place of a scraper or similar device used by engravers for lowering those portions of a plate which are not to be printed from. Not only is, this true, but the over-etching process affords a soft and delicate outline that causes a gradual blendmg of all the tints in the printed picture.

After the original plate and the shadow plates for thesame have been readily produced, as above described, they are mounted upon blocks, so as to render them as high as type, and enable them to be printed from, on a suit able press. The desired number of impressions are first taken from the original plate A, the ink'used for this purpose being of a light tint, to give the proper aerial perspective tothe sky and distant hills, and when these impressions are dry, the first shadow plate B is brought into service. In using this plate, a deeper-toned ink is employed, for the purpose of strengthening the middle distance, and after the second printing is dry, the final shadow-plate C is printed from, the ink for this last impression being materially darker than any previously applied, so as to bring out the foreground trees and shrubbery very strongly and distinctly. Consequently, the finished print will appear as seen at D, in Fig. 4, the sky, distant hills, reflections in the water, and in fact all the light tones being the only portions visible that were printed from the original plate A, while the middle distance shows this first impression with the second printing imposed over it, and the foreground exhibits an unusual depth of color due to all the near objects having received three separate impressions. Hence, the sky and extreme distance are light and airy, the middle distance more distinct, and the foreground sharp and well defined, which blending or gradation of tints is effected without blurring or confusion, on account of the perfect registry occasioned by all the plates being made from a single photographic positive or negative. Finally, in some cases it may be advisable to use different colored inks with the various plates, or'to em ploy three or more shadow-plates with a single origina but such changes are included in my invention, as is also the great number of subjects capable of being illustrated by it.

I claim as my invention- 1. A series of relief plates for printing pictures, consisting of an original plate having all the detail of the picture thereon, and a secondary plate, or secondary plates, from which portions of the detail have been removed by over etching, the amount of detail removed increasing with each successive plate, substantially as described.

2. The improvement in the art of producing pictures by printing from etched relief-plates, which consists in, first making on the blank surface of a plate a delineation in asphaltum or equivalent resist, of the picture in all its details, etching the same into relief, andprinting with the plate so etched an impression on paper, then treating a second blank plate in like manner, and after the development of full detail thereon, continuing the solvent action of the acid for the production of a shadow plate by over etching, then printing with the shadow plate so produced an impression upon and in register with the first impression on paper, and in the same way producing and printing as many shadow plates, of successively-diminishing surface, as are required for the finished design, substantially as herein described.

3. That improvement in making reliefplates, which consists infirst producing exact duplicates from a single photographic positive or negative, and then destroying the more delicate portions of one of them by etching, thereby aifording an original plate and a shadow plate, the preserved part of which latter is a fac simile of the corresponding portion of said original, but has the edges of its masses softened by being over etched, substantially as herein described.

4. That improvement in making reliefplates, which consists in first producing a number of exact copies from a single phot0- graphic positive or negative, and then destroying the more delicate portions of all except one of them by etching, so as to atford an original and a series of shadow plates, the preserved portions of which latter are exact fac similes of the corresponding parts of said original, but have successively-diminishing surfaces, the edges of the masses thereof being softened by over etching, substantially as herein described.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN F. EARHART.

Witnesses:

JAMES H. LAYMAN, SAMUEL M. QUINN. 

